X.-A. Wang

Learn More
If a primary physiologic action of TRH is to regulate the set-point for negative feedback, a sudden drop in plasma thyroid hormone concentration should stimulate the same rate of in vivo increase in TSH secretion from normal and TRH-deprived thyrotrophs. To test this hypothesis, 3 experiments were performed in which young adult female rats were divided into(More)
Blocking K+ channels induces hormone secretion in various pituitary cell lines by a mechanism which is not completely delineated. In the present study, we employed the mouse pituitary tumor-derived AtT-20 cell as a model to evaluate this phenomenon. We correlated the effect of the K+ channel-blocker, tetraethylammonium (TEA), on K+ current and membrane(More)
We utilized luteinizing hormone-releasing hormone (LHRH) secretion by perifused minced rat hypothalamic median eminence (ME) tissue to evaluate whether isotonic ethanol would stimulate neurosecretion as it does secretion from pituitary cells. Isotonic ethanol induced a dose-dependent burst of LHRH secretion which was maximal at 2-3 min and returned to near(More)
Imidazole-4-acetic acid-ribotide (IAA-RP), an endogenous agonist at imidazoline receptors (I-Rs), is a putative neurotransmitter/regulator in mammalian brain. We studied the effects of IAA-RP on excitatory transmission by performing extracellular and whole cell recordings at Schaffer collateral-CA1 synapses in rat hippocampal slices. Bath-applied IAA-RP(More)
Medium hyposmolarity between 10 and 50% and isotonic urea between 22.5 and 90 mM induced a dose-dependent burst of gonadotropin-releasing hormone (GnRH) secretion from perifused median eminence tissue which was maximal at 2-3 min and returned to near baseline by 5 min in spite of continued exposure to the stimulus. If Ca(2+)-free medium was used, osmotic(More)
Medium hyperosmolarity between 300 (normal medium osmolarity) and 600 mOsm inhibited in a concentration-correlated fashion (r greater than 0.97, p less than 0.001) the rise in intracellular Ca2+ concentration ([Ca2+]i) and prolactin (PRL) secretion induced in GH4C1 cells by depolarizing 30 mM K+. [Ca2+]i concentration and PRL secretion were tightly related(More)
The mechanism of the inhibitory effect of local anesthetics on hormone secretion was studied in the GH4C1 line of rat pituitary tumor-derived cells. Lidocaine between 0.1 and 5 mM exerted significant dose-dependent inhibition on the increment in cytosol Ca2+ concentration ([Ca2+]i) and prolactin (PRL) secretion induced by 30 mM K+. For both effects the IC50(More)
We studied the influence of graded degrees of hyperosmolarity on the dynamics of the thyrotropin-releasing hormone (TRH)-induced rise in cytosol Ca2+ concentration ([Ca2+]i) and prolactin (PRL) secretion in GH4C1 cells. TRH caused two phases of increase in [Ca2+]i that were differentially altered by hyperosmolarity: 100% hyperosmolarity (600 mOsm) depressed(More)
Cell swelling produced by a variety of techniques is a potent stimulus intensity-related inducer of an immediate secretory burst of thyroid-stimulating hormone (TSH) and prolaction (PRL) secretion from anterior pituitary cells. A 2-min "square wave" exposure to either hyposmolarity or isotonic urea induced stimulus intensity-correlated TSH and PRL secretory(More)
We evaluated the role of Ca(2+)-activated K+ channels in the regulation of prolactin (PRL) secretion with a perifusion system using acutely dispersed rat anterior pituitary cells. Apamin, which blocks Ca(2+)-activated K+ channels, induced PRL secretion in a dose-dependent fashion between 1 and 300 nM (r = 0.99, P < 0.01). Charybdotoxin, another(More)